Centrifugal replenishing pump for a hydrostatic pump motor system

Abstract

In a radial piston pump-radial piston motor drive system, a centrifugal replenishing pump is provided integral with the pump driving means. The radial-piston pump, radial piston motor, centrifugal replenishing pump, and most of the fluid circuit, including fluid sump are all contained within a unitary housing to provide a compact self-contained pump-motor hydrostatic unit.

The embodiment of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. In an hydrostatic pump-motor system including a housing enclosing a hydrostatic pump having rotor means with an input shaft thereto and an hydrostatic motor driven by hydraulic fluid forced from said pump, the improvement comprising: centrifugal pump means integral with said rotor means and internally within said housing and in driven connection with said input shaft, the centrifugal pump means replenishing said pump by providing an additional source of hydraulic fluid thereto; and, a plurality of passageways within said housing which communicate a sump chamber for said system to the centrifugal pump means, which communicate outlet hydraulic fluid from the centrifugal means to fluid inlets for said hydrostatic pump, and which communicate pressurized fluid from said centrifugal pump to bearing surfaces of said hydrostatic motor.   
     
     
       2. The system of claim 1 wherein pressure-sensitive valves regulate the flow of hydraulic fluid through the passageways which communicate the outlet hydraulic fluid from the centrifugal pump means to fluid inlets for said hydrostatic pump, the valve means regulation responsive to pressure in the fluid inlets falling below a predetermined level. 
     
     
       3. The system of claim 1 wherein passageways communicate hydraulic fluid from said centrifugal pump through pump and motor and thence to a filter and from thence to the sump chamber for said system, to provide continuous filtration of hydraulic fluid within said system. 
     
     
       4. The system of claim 1 wherein fluid output from said centrifugal pump lubricates said hydrostatic pump. 
     
     
       5. The system of claim 1 wherein said centrifugal pump comprises a first stage including bladed impeller means and a second stage comprising passages defined by hydrostatic pump cylinders.